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238 Appendices

3000
Minimum Required Air Injection Rate (scfm) 2000 Q =4 bbl/hour
2500

1500
w
Q =8 bbl/hour
w
1000
Q =12 bbl/hour
w
Q =16 bbl/hour
w
500
w
Q =24 bbl/hour
w
For cuttings removal
0 Q =20 bbl/hour
0 2000 4000 6000 8000 10000 12000 14000 16000
Depth (ft)
Figure B.9 Calculated air injection requirements for drilling a 6¼-in hole with a 2⅞-in
drill pipe at an ROP of 60 ft/hr (water-air interfacial tension = 40 dynes/cm).

3000 Q =4 bbl/hour
Minimum Required Air Injection Rate (scfm) 2000 Q =16 bbl/hour
w
Q =8 bbl/hour
w
2500
Q =12 bbl/hour
w
w
Q =20 bbl/hour
w
Q =24 bbl/hour
w
For cuttings removal
1500
1000
500
0
0 2000 4000 6000 8000 10000 12000 14000 16000
Depth(ft)
Figure B.10 Calculated air injection requirements for drilling a 4¾-inholewitha
2⅜-in drill pipe at an ROP of 60 ft/hr (water-air interfacial tension = 60 dynes/cm).